This invention relates to portable drive systems for shallow bottom boats, especially for such boats intended for operation in weed infested waters and/or in shallow waters with rocky beds.
It is well known that excellent fishing areas are often found in waters that may be weed infested and/or have shallow or rocky bottoms. Such conditions are impossible for conventional outboard motor drive systems and even very difficult for shallow draft trolling motor drive systems. In a conventional transportable trolling motor drive system, a small electric motor and propeller are suspended in the water by a steering handle mechanism that is removably supported by means of a bracket attached to the transom of a boat. Because of the drive system size and configuration, Le., the relatively large in-the-water profile of the motor, propeller and vertical support, weeds tend to catch. This drastically affects motor speed and efficiency and requires frequent stops to manually remove weed buildup. Since the diameter of the propeller is greater than the large diameter of the motor, the motor is operated at low rotation to provide proper low trolling speeds. The low motor rotation is not conducive to cutting and churning through weeds.
The weight of the motor also presents a problem. Because of the high inertia of the motor in the water, there is an increased possibility of propeller breakage or motor damage should obstacles be encountered. While there are systems described in the prior art for powering shallow draft boats under such conditions, they either involve significant modification of the boat transom or an unusual propulsion arrangement, such as fitting a propeller drive arrangement to an oar. Such systems have not found favor and none are known to be in use.
A practical shallow water, weed-resistant boat drive system should ideally: be lightweight; mount directly to a common boat transom; be readily transportable without requiring breakdown into component parts; present a minimal in-the-water profile; be capable of withstanding impacts with submerged articles; and have the ability to either shed, slice or churn through most weeds that are encountered.
As discussed above, the prior art systems fail to meet one or more of the above criteria. Drive systems that have the drive motor in the water do not present a minimal in-the-water profile, are ineffective in cutting, slicing or churning through weeds and are very susceptible to damage by impact with objects. Drive systems that have only a propeller in the water are very cumbersome, primarily due to the very long propeller shafts needed to achieve a favorable propulsion angle. None of the drive systems supports the propeller in the ideal position for weed resistance, ie., just beneath the water surface with the propeller axis parallel to the water surface.
U.S. Pat. Nos. 4,604,067 and 4,976,637 describe unusual trolling motor drive systems that utilize conventional hand-held, gasoline engine-powered weed cutting machines. The weed cutting machines include a bent tubular housing having a motor at one end and a rotating trimmer line cutting mechanism at the other end, with a flexible shaft, encased by the tubular housing, coupling the motor and the cutting mechanism. The cutting mechanism is replaced with a small propeller, and a clamping device is added to support the drive system from the transom of a boat. The bent tubular shaft, due to its radius of curvature, supports the propeller at an unfavorable propulsion angle in the water. The devices represent low cost trolling motor arrangements and, while exhibiting certain structural similarities, are not concerned with the problems addressed by the present invention and are clearly ineffective in operating in a weedy environment.
The present invention provides a motor drive system that meets all of the above described criteria and does so in a very simple, economical manner. It will be appreciated that others, such as hunters who use boats, often encounter similar weedy and shallow and/or rocky water conditions where the invention will be of significant benefit. The invention is also easily adapted for attachment to various inclined surfaces, such as the walls or gussets of a canoe, or for use on the bow of curved hull boat.
A principal object of the invention is to provide a novel motor drive system for a boat.
Another object of the invention is to provide a motor drive system that is capable of providing continuous operation of a boat in shallow rocky and/or weedy water.
A further object of the invention is to provide a lightweight, unitary portable weed and impact resistant motor drive system for a boat.